Study on pollution control and thermal efficiency optimisation of tobacco bulk curing barn
Coal is still used as a fuel to provide the necessary heat for most tobacco curing barns in China. Due to the lack of corresponding equipment and the measures to reduce emissions, the gas pollutants from curing barns, such as SO2, smoke, etc., are often discharged into the atmosphere without any processing, and it causes serious pollution to the environment. To solve the pollution problem of SO2 and particulate matter (PM) during fuel combustion in tobacco barns, this study investigated the pollutant emission properties and mechanisms of tobacco barns in five provinces, i.e. Hu Bei, Fu Jian, Gui Zhou, Yu Nan and He Nan. Equipment was designed to control the emission of SO2 and PM according to emission properties, and the effect of the equipment was verified. The results showed that desulfurisation and dedusting efficiency were in the range of 75-90 % and the concentration of pollutants was lower than the corresponding emission standards with the use of the equipment. There was a large heat loss in the tobacco barn, i.e. the heat loss of exhaust gas was 10-20 % and the heat loss of incomplete combustion was 4-11 %. The thermal efficiency of the curing room was calculated by the indirect balance method, and the calculation results showed that the thermal efficiency of the tobacco barn at the five demonstration sites was 25-45 %. Moreover, the fuel-rich region with a high thickness of coal seam in furnace caused a high pollutant emission and a large heat loss. However, the use of automatic continuous coal feeding equipment could effectively reduce the emission of pollutants and the loss of heat, and also improve the thermal efficiency of the tobacco curing room. Therefore, the use of desulfurisation dedusting facilities and automatic coal filling techniques could significantly reduce pollutant emissions in bulk curing barns.